Hybridization experiments will be performed using a vast meiotic cell poly(A)-containing RNA extracted at specific periods during meiosis and complementary DNA (cDNA) made from each RNA preparation, to describe the complexity of meiotic yeast poly(A)-containing RNA. The number and distribution of poly(A)-containing RNA sequences of meiotic cells will be compared to that which is observed in mitotic cells immediately prior to the onset of meioses. A complexity analysis of RNA will also be made of asporogenic diploids which are homozygous for mating type alleles and selected meiotic mutants under conditions that normally trigger the meiotic process in sporulation-competent cells. The fraction of poly(A)-containing RNA which is meiosis- or sporulation-specific will be determined at intervals throughout sporulation by cross hybridization of cDNA made from sporulation RNA with vegetative RNA. The 3H-cDNA which is not complementary to poly(A)-containing RNA of vegetative yeast by complementary with sporulation whole-cell RNA will constitute the sporulation-specific sequences. The transcription of these sequences will be studied in asporogenic diploids homozygous for mating type alleles and selected meiotic mutants. A urea-soluble protein which is obtained from ascospores, and currently thought to be the ascospore coat protein, will be isolated and further characterized with respect to is biochemical properties and regulation of synthesis. Immunological and radioisotopic labeling procedures will be utilized to charaterize its synthesis in wild type and meiotic mutant cells.